Manufacturers of complex workpieces and assemblies requiring a high degree of assembly accuracy are continuously looking for improved processes with the use of assembly aids. While conventional manufacturing processes have historically relied on mechanical fixtures as assembly aids that register to a workpiece at a fixed location, these mechanical fixtures have proven difficult to work with and do not provide sufficient accuracy whenever decreasing tolerances are required of complex devices. Alternatively, manual measurement of attachment locations using various reference features or templates applied to the workpiece have also been used. The expense, labor intensive requirements, and propensity for error continue to be a challenge to manufacturing companies.
FIG. 1 shows a schematic view of a workpiece 10. The workpiece 10 includes a component (or subassembly) 12 mated to a surface 16 at a geometrically significant location. As set forth above, accurate location of the component 12 to the workpiece 10 has been achieved with the use of a fixture. Accuracy is particularly inadequate when the fixture is large or heavy making it difficult for an operator to position properly on the workpiece 10.
More recently, optical templates have been projected directly onto workpieces providing an optical image to locate placement a component onto the workpiece 10. This is represented in FIG. 2 where the workpiece 10 is subject to a laser projector 12 that projects a template 14 onto a pre-determined surface 16 of the workpiece. One such example of a laser projector 12 used to project a template 14 onto workpiece 10 is disclosed in U.S. Pat. No. 9,200,899 LASER PROJECTION SYSTEM AND METHOD, the contents of which are incorporated herein by reference. In this example, the position of the projector 12 relative to the workpiece along with a three dimensional geometry of the workpiece and profile of the attachment location are predetermined. Making use of these elements, an outline of an attachment profile in the way of an optical template 14 is accurately projected onto the desired workpiece surface 16.
Systems used to project templates 14 onto a workpiece have proven highly accurate. However, there are limitations to relying merely on a laser projection of a template 13 restricting broader use of optical templates in the marketplace. For example, it is sometimes difficult or impossible to locate a workpiece within a three dimensional coordinate system relative to a laser projector. In addition, arbitrary assembly tasks traditionally make use of mechanical fixtures placed in arbitrary three dimensional locations are not always uniquely suited to laser projection templates 14. In some circumstances, a support surface is available, but the only accurate projection of a profile template is capable upon a first surface of the workpiece. In addition, the three dimensional component affixed to a workpiece prevents projection of a pattern that “looks like” the component when it is necessary to verify correct component selection, placement or orientation.
Projection of a laser template 14 is typically flattened to be received upon a surface of a workpiece. Presently, laser projectors are incapable of providing an accurate focal point at a location spaced from the surface 16 of a workpiece. This prevents projection of a true location of the component according to a computer aided design model that is three dimensional or includes relevant geometrically important features that would be floating in space above the surface 16 of the workpiece 10.
Therefore, it would be desirable to provide a method for overlaying an image of a component to be assembled in a workpiece that provides three dimensional characteristics of that component relative to the workpiece.